| 摘要 |
PROBLEM TO BE SOLVED: To provide a filter where a resonator part consisting of a dielectric substrate formed with an electrode pattern is reduced in size and its no load Q is enhanced and that is downsized and to provide a duplexer and a communication unit using them. SOLUTION: Center electrodes 2a, 2b respectively having an open end, and a surrounding electrode 3 extended along both sides of them are formed on the upper side of the dielectric substrate 1 and center electrodes 4a, 4b and a surrounding electrode 5 opposed respectively to the center electrodes 2a, 2b and the surrounding electrode 3 are formed on the lower side of the dielectric substrate 1.
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